121,144 research outputs found
Towards understanding the probability of ground states in even-even many-body systems
For single- shells with and 11/2, we relate the large
probability of ground states to the largest (smallest) coefficients
, where is the particle number, is the seniority, is an
additional quantum number, and is the angular momentum of the state.
Interesting regularities of the probabilities of ground states are
noticed and discussed for 4-particle systems. Several counter examples of the
ground state (0GS) predominance are noticed for the first time.Comment: 5 pages, 1 figure. Phys. Rev. C64, in pres
Energy Centroids of Spin States by Random Two-body Interactions
In this paper we study the behavior of energy centroids (denoted as
) of spin states in the presence of random two-body
interactions, for systems ranging from very simple systems (e.g. single-
shell for very small ) to very complicated systems (e.g., many- shells
with different parities and with isospin degree of freedom). Regularities of
's discussed in terms of the so-called geometric chaoticity (or
quasi-randomness of two-body coefficients of fractional parentage) in earlier
works are found to hold even for very simple systems in which one cannot assume
the geometric chaoticity. It is shown that the inclusion of isospin and parity
does not "break" the regularities of 's.Comment: four figures. to appear in Physical Review
Comparative study of in situ and ex situ MgB2 films deposited by pulsed laser deposition
Two types of MgB2 films were prepared by pulsed laser deposition (PLD) with
in situ and ex situ annealing processes respectively. Significant differences
in properties between the two types of films were found. The ex situ MgB2 film
has a Tc of 38.1K, while the in situ film has a depressed Tc of 34.5K. The
resistivity at 40K for the in situ film is larger than that of the ex situ film
by a factor of 6. The residual resistivity ratios (RRR) are 1.1 and 2.1 for the
in situ and ex situ films respectively. The Jc-H curves of the in situ film
show a much weaker field dependence than those of the ex situ film,
attributable to stronger flux pinning in the in situ film. The small-grain
feature and high oxygen level may be critical for the significant improvement
of Jc in the in situ annealed MgB2 film.Comment: 6 pages, 6 figure
Accurate Modelling of Left-Handed Metamaterials Using Finite-Difference Time-Domain Method with Spatial Averaging at the Boundaries
The accuracy of finite-difference time-domain (FDTD) modelling of left-handed
metamaterials (LHMs) is dramatically improved by using an averaging technique
along the boundaries of LHM slabs. The material frequency dispersion of LHMs is
taken into account using auxiliary differential equation (ADE) based dispersive
FDTD methods. The dispersive FDTD method with averaged permittivity along the
material boundaries is implemented for a two-dimensional (2-D) transverse
electric (TE) case. A mismatch between analytical and numerical material
parameters (e.g. permittivity and permeability) introduced by the time
discretisation in FDTD is demonstrated. The expression of numerical
permittivity is formulated and it is suggested to use corrected permittivity in
FDTD simulations in order to model LHM slabs with their desired parameters. The
influence of switching time of source on the oscillation of field intensity is
analysed. It is shown that there exists an optimum value which leads to fast
convergence in simulations.Comment: 17 pages, 7 figures, submitted to Journal of Optics A Nanometa
special issu
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